Serdar Gunaydin

Clinical performance and biocompatibility of poly(2-methoxyethylacrylate)-coated extracorporeal circuits

BACKGROUND Poly(2-methoxyethylacrylate) is an amphiphilic organic polymer consisting of a hydrophobic backbone with pendant hydrophilic groups that has been reported to reduce protein and platelet adsorption in in vitro and ex vivo studies. METHODS Sixty patients undergoing three-vessel coronary artery bypass grafting were divided into two equal groups. Group 1 had operation with Capiox poly(2-methoxyethylacrylate) coated SX18R oxygenators with noncoated circuits, and group 2 had operation with all noncoated circuits. Hemodynamic variables, blood and urine test results, hematologic variables, complement fractions, C3a and C4d, and interleukin-6 levels were documented preoperatively (T1), on cardiopulmonary bypass (T2), before cessation of cardiopulmonary bypass (T3), after protamine sulfate reversal (T4), and on the first postoperative day (T5). Protein electrophoresis was performed at T1 and T5. Blood cell adhesion and aggregation on fibers were analyzed with optical microscopy, and desorbed protein was evaluated quantitatively by a spectrophotometer using samples obtained when the oxygenators were dismantled after cardiopulmonary bypass. RESULTS Platelet counts in group 1 demonstrated significant differences at T3, T4, and T5 (p < 0.05) versus group 2 and white blood cell counts in group 1 versus group 2, at counts T4 and T5. Albumin levels were significantly better preserved in group 1 at T4, and T5 and fibrinogen levels, at T3 and T5 (p < 0.05). On electrophoresis, the postoperative albumin level was 57.9% +/- 3% in group 1 versus 50.2% +/- 3% in group 2 (p < 0.05). Postoperative hemorrhage was 452 +/- 35 mL in group 1 and 612 +/- 35 mL in group 2 (p < 0.05). Duration of intubation was significantly lower (p < 0.05) in group 1, as was need of blood transfusion (p < 0.01). More platelet adhesion and aggregation were demonstrated on noncoated oxygenator fibers. The amount of desorbed protein was 0.13 +/- 0.01 mg/dL versus 0.012 +/- 0.001 mg/dL (p < 0.001) on noncoated versus coated fibers, respectively. CONCLUSIONS Poly(2-methoxyethylacrylate)-coated oxygenators reduce platelet adhesion, platelet aggregation and protein adsorption. This surface provides a better perioperative clinical status through platelet-, albumin-, and fibrinogen-sparing effects.

Amiodarone versus digoxin and metoprolol combination for the prevention of postcoronary bypass atrial fibrillation

OBJECTIVE This prospective randomized study aims at evaluation and comparison of the prophylactic effects of amiodarone versus digoxin and metoprolol combination in postcoronary bypass atrial fibrillation. METHODS A total of 241 consecutive patients undergoing elective coronary artery bypass grafting were randomly allocated into three groups. Patients in Group1 (n=77) received metoprolol 100 mg/24 h per oral (P.O.), preoperatively, 2x0.5 mg digoxin intravenously on the operating day and digoxin 0.25 mg P.O.+metoprolol 100 mg P.O. on the first postoperative day until discharge. Patients in Group 2 (n=72) received totally 1200 mg intravenous/24 h amiodarone which the 300 mg - bolus dose/1 h was given as soon as the operation had been finished. On the next day patients were administered 450 mg/24 h amiodarone i.v. and 600 mg/day in three doses P.O. were given until discharge. Group 3 (n=92) was the control group with no antiarrhythmic prophylaxis. RESULTS Preoperative patient characteristics and operative parameters were similar in three groups. Atrial fibrillation occurred in 13 patients (16.8%) in Group 1, six patients (8.3%) in Group 2 and 31 patients (33.6%) in Group 3. CONCLUSION Both study groups were effective in the prevention of postcoronary bypass atrial fibrillation with respect to control (P<0.01 in Group 1 and P<0.001 in Group 2).

Psychiatric complications of cardiac surgery postoperative delirium syndrome.

Psychiatric disturbances due to cardiopulmonary bypass, especially postoperative delirium syndrome, are among the immediate complications of open-heart surgery. In a series of 32 male and 18 female patients the prevalence of such disorders was investigated and search was made for possible risk factors for their occurrence. Psychiatric, neurologic and electroencephalographic evaluation was made pre- and postoperatively, in addition to haemodynamic, echocardiographic, angiographic and regional cerebral blood flow studies. Nine of the 50 patients had significantly reduced perfusion of certain cerebral lobes in single photon emission computed tomography, and in six of them the psychiatric tests indicated postoperative delirium; three of these six also had moderate electroencephalographic changes. The cerebral hypoperfusion persisted on day 15 in four patients, while psychiatric tests were negative. The study showed possible risk factors to be patient age, long aortic cross-clamp time, high-dose inotropic support and excessive transfusion of blood or blood products.

The effects of vasoactive intestinal peptide on monocrotaline induced pulmonary hypertensive rabbits following cardiopulmonary bypass: a comparative study with isoproteronol and nitroglycerine.

BACKGROUND Vasoactive intestinal peptide (VIP) has regulatory effects on myocardial and vasomotor functions usually demonstrated by in vitro or isolated heart studies. We studied in vivo effects in monocrotaline induced pulmonary hypertensive rabbits immediately after cardiopulmonary bypass (CPB) and tested them versus calcium channel and beta-blockers. METHODS The study consisted of six groups (N=30; five rabbits/group): (1) Control with no pretreatment, monocrotaline injected groups: (solutions were perfused following termination of CPB for 60 min); (2) Control for pulmonary hypertension (PHT); (3) isoproteronol; (4) VIP 10(-6) M; (5) VIP 10(-5) M; (6) nitroglycerine. Normothermic CPB was instituted in thirty rabbits at a flowrate of 100 ml/kg/min for 120 min. Heart rate, mean arterial pressure (MAP), central venous, left atrium (LAP), pulmonary artery (PAP) pressures, pulmonary resistance (Rp), blood gases and ions were measured before and 15, 30, 45 and 60 min after CPB. The VIP 10(-5) M group was subjected to an additional 1.7 x 10(-6) M propranol and 2 mM verapamil infusions for a further 15 min. RESULTS LAP, PAP, Qp, and Rp were significantly higher in the PHT control group (P<0.001). VIP 10(-5) M increased MAP and decreased PAP significantly with respect to isoproteronol and VIP 10(-6) M (P<0.05). VIP 10(-5) M also decreased Rp significantly in the early post CPB 15th minute (P<0.05), but did not show any superiority to other agents in the following minutes. Verapamil inhibited VIP 10(-5) M effects but propranol did not. CONCLUSION VIP has dose responsive, positive inotropic and pulmonary vasodilatory effects in whole body CPB model acting via calcium channels.

Clinical evaluation of minimized extracorporeal circulation in high-risk coronary revascularization: impact on air handling, inflammation, hemodilution and myocardial function

Objective: We examined intraoperative microembolic signals (GME), inflammatory response, hemolysis, perioperative regional cerebral oxygen saturation (rSO2), myocardial protection and desorbed protein amount on oxygenator fibers in high-risk patients undergoing coronary revascularization (CABG) with minimized and conventional cardiopulmonary bypass (CPB). Methods: Over a ten-month period, 40 Euroscore 6+ patients undergoing CABG were prospectively randomized to one of the two perfusion protocols (N=20): Group 1: minimized extracorporeal circuits (Mini-CPB) (ROCsafe MPC, Terumo, Ann Arbor, MI, USA) and Group 2: conventional extracorporeal circuits (CECC) (Capiox SX18, Terumo, USA). Serum creatinine kinase-MB (CKMB), free hemoglobin, interleukin-6 (IL-6) and C3a levels were measured. Blood samples were collected at T1: following induction of anesthesia; T2: thromboelastography control; T3:15 min after commencement of CPB; T4: before cessation of CPB; T5: 15 min after protamine reversal and T6: ICU. Results: Serum IL-6 levels were significantly lower in the Mini-CPB group at T4 and T5 and C3a levels were significantly less in the Mini-CPB group at T3, T4 and T5 vs. CECC (p<0.01). CKMB levels in coronary sinus blood demonstrated well preserved myocardium in the Mini-CPB group. Percentage expression of neutrophil CD11b/CD18 levels were significantly lower in the Mini-CPB group at T4 and T5 (p<0.05). There were no significant differences in air handling characteristics or free plasma hemoglobin levels in either circuit. rSO2 measurements were significantly better at T3 and T4 in the Mini-CPB vs. CECC (p<0.05) and always higher in the Mini-CPB during follow-up. Blood protein adsorption analysis of oxygenator membranes demonstrated a significantly increased amount of microalbumin on CECC fibers (p<0.05). Conclusion: Mini-CPB provided a comfort and safety level similar to conventional control via satisfactory air handling, attenuated inflammatory response and hemodilution, with a better clinical outcome in patients undergoing high-risk CABG.

Angiographic Assessment of Sequential and Individual Coronary Artery Bypass Grafting

Abstract  Objective: In trying to answer the question about the controversial use of sequential grafts, we determined the mid‐term angiographic outcome of patients in whom coronary artery bypass was performed with different types of vein grafts. Methods: A total of 1034 coronary anastomoses on 724 saphenous vein grafts (SVGs) (apart from 497 left internal mammarian artery (LIMA) anastomoses) were assessed in 509 patients in an average of 55.4 ∓ 17.6 months after coronary artery bypass grafting. Results: The patency rates of sequential conduits were markedly higher than those of individual ones (86.6% vs 69.6%, p = 0.0001). Also, the anastomoses on the sequential conduits had better patency rates (80.6% vs 69.6%, p = 0.0001). This difference was even more pronounced in coronary arteries of poor quality/small (<1.5 mm) diameter (68.9% vs 51.6%) for the sequential and individual grafts, respectively (p = 0.03). Also, the patency of the entire sequential conduit was lower when most distally located anastomosis was of poor runoff (45.2%). Conclusions: The patency of a sequential vein conduit is generally superior than that of an individual one, especially for poor runoff coronary vessels, provided that the most distally located anastomosis is performed on a good coronary artery in terms of quality and diameter. Using a minimal length of SVG is another advantage. However, failure of a single sequential conduit jeopardizes all of the anastomoses along that graft segment. Besides, being technically more demanding, technical expertise in performing a sequential anastomosis is probably among the important predictors of patency. (J Card Surg 2003;18:524‐529)

Clinical significance of coated extracorporeal circuits: a review of novel technologies

Coating of extracorporeal circuits may be a solution to prevent adverse effects induced by the contact of blood elements and proteins with foreign surfaces. This paper reviews the recent novel coating technologies and compares their documented in vitro and ex vivo advantages under the clinical setting. Data presented have also been supported by postclinical biomaterial research to verify biocompatibility and hemocompatibility.

An unusual experience with posterior pericardiotomy

There are some recent reports on the effect of posterior pericardiotomy to the postoperative supraventricular tachyarrythmias (SVT). Although controversy still exists on its effect on atrial ®brillation, its clinical bene®t on pericardial tamponade is satisfactory [1±3]. To test its effectiveness on SVT we started performing posterior pericardiotomy where we experienced an unusual case on the 29th patient. A 55 year old man with left main coronary stenosis besides two vessel disease, normal ventriculography and ejection fraction 65% was operated in standard fashion with a roller pump, non-pulsatil ̄ow (2.0±2.4 l/min), Polystan membrane oxygenator, 328C systemic hypothermia, single cross clamp, initial antegrade 1 retrograde cold blood cardioplegia, repeated cold retrograde blood cardioplegia every 20 min, and a hot shut before the removal of the cross clamp. LIMA grafting to the LAD and sequantial saphenous graft to ®rst diagonal, intermediate and obtuse marginal arteries were performed. After an uneventful operation ( £ clamp time 42 min, total perfusion time 58 min) the patient was placed in the ICU ward where the patient deteriorated with lateral ST elevation and multifocal ventricular arrhythmias, which did not respond to the medical therapy, continued with ventricular ®brillation (VF), which also did not respond to de®brillation. The patient returned to the operating room urgently and re-explored. After reopening the sternum VF had been over come following the ®rst de®brillation with internal paddles. The hemodynamia returned to normal in a short time with positive inotrops followed by ST normalisation. All the bypass grafts were patent, nothing unusual was observed. Following haemostasis sternum was wired again. But by the time of cutaneous sutures, the ST elevation relapsed, the hemodynamia failed quickly, VF re-occurred. The sternum was reopened in a short time and the heart was de®brillated again. Grafts were patent again, but an ischaemic colour change was observed on the lateral and posterior aspect of the heart. On careful examination we had observed that a segment of saphenous graft (just before and after the intermediate artery anastomosis) and left atrial appendage protruded from the posterior pericardiotomy. The saphenous graft was squeezed by the edges of the posterior pericardiotomy incision. After closing the posterior pericardiotomy incision by primary sutures, and insertion of an intra-aortic balloon from left femoral artery the patient was taken to the ICU ward again. Reperfusion arrhythmia was controlled by amiodorone infusion. Postoperative peak CK-MB (mass) value was 42 ng/ml and Troponin T was 4.85 ng/ml, no Q waves were noted in electrocardiograms. Following an uneventful 5 days in the ICU the patient was discharged in his 10th postoperative day with lateral hypokinesia in echocardiography taken on the 8th day postoperatively. Posterior pericardiotomy is effective on early and late pericardial tamponade, can be effective on the incidence of SVT, but after this case in our opinion, should carefully be used with patients in whom posterior wall revascularization was performed especially by sequential grafting.

Clinical impact and biomaterial evaluation of autologous platelet gel in cardiac surgery

We compared the clinical efficacy of autologous platelet gel (APG) and gelatine (CONT), including biomaterial evaluation. In a prospective, randomized, controlled trial, 64 patients undergoing complex coronary artery bypass graft (CABG) surgery and/or aortic surgery, in whom the surgeon was able to identify a bleeding site for which conventional means to stop bleeding were impractical or proved unsuccessful, were enrolled. Aortic punch biopsy from each patient was harvested in explant cell (EC) culture media. Hemostasis success for the “oozing” category was 89% in APG and 60% in CONT (p< 0.05). For the “heavy bleeding” category, the success rates were 92% in APG and 45% in CONT (p<0.01). Contact of gelatine inhibited EC proliferation and APG increased cell cycling and EC quantity. Phagocytic capacity (PC) was significantly higher in the APG group (p<0.001). APG was significantly better than CONT with respect to hemostatic success rate, effects on wound healing and increased resistance to infection (PC).

Influence of hematocrit and pump prime on cerebral oxygen saturation in on-pump coronary revascularization

Background: The couplings between cerebral oxygenation (rSO2), on-pump hematocrit and circuit prime are explored in this study. Methods: Thirty-eight consecutive patients undergoing coronary revascularization with cardiopulmonary bypass (CPB) were matched on preoperative hematocrit < 40% and >40% (n=16). Similarly, six blood prime patients were matched with six crystalloid prime patients. Hematocrit and rSO2 levels were then compared on CPB. Results: The pre-operative hematocrit >40% group retained higher levels on pump run (p < 0.01) and significantly higher rSO2 prior to CPB (64.8±9.6 versus 73.2±7.3), and on and off CPB (61.1±8.8 versus 67.4±6.4). Blood priming increased absolute rSO2 (2.3± 6.3 versus − 10.9±5.9) and% rSO2 (4.7±11.8 versus −14.2±7.4%) in the low hematocrit group. Conclusion: Blood primes are instrumental in high-risk and low preoperative hematocrit patients in preventing cerebral oxygen desaturation during initiation and maintenance of CPB.